Communication networks are an integral part of everyday life. A variety of tasks, both complex and mundane, are effectively and quietly monitored and controlled by computer networks without requiring constant human interaction. Networks can interconnect several devices or modules for controlling and monitoring an environment, process or task. The devices and/or modules can be linked together via a communication cable. These devices include, computers, programmable logic controllers, sensors, gauges, monitors, display terminals, valves, motors, machinery, alarms, etc.
As networks become more reliable, society becomes more dependent on them. Ironically, the more dependent society becomes on networks, the more difficult it is to manage everyday operations when the network fails to function properly. Because the modules are interconnected, problems occurring with one module or section of the network can affect other parts of the network.
Network modules communicate with each other via a communication bus, e.g., Ethernet. Ethernet networks encompass a variety of network structures or topologies, i.e., bus, star, as well as utilizing different types of transmission cabling, i.e., co-axial cable, twisted-pair and unshielded twisted-pair lines. Network problems can occur through the failure or removal of an individual module, device or sub-network in the network. If the bus is severed or if a network module is removed or replaced, the electrical characteristics of the bus are affected; namely, the electrical impedance characteristics of the transmission bus throughout the network. When the impedance characteristic of the bus is not matched within the network, the communication signals are adversely affected and the signal transmission can be corrupted.
To combat network problems, Ethernet networks are often configured in a star topology. FIG. 1. The star topology resolves network disruptions caused by removal of a network module or separation of the communication cable by providing for the disruption to affect only the specific branch of the communication cable. Although the star topology is beneficial, additional cabling and network devices, e.g., hubs, are required. The additional equipment increases the overall cost and complexity of the network.
This invention is directed to solving these and other problems.